Replacing a tank water heater

At a glance

Common sizes

Roughly 40 to 60 US gallon residential tanks

Fuel

Natural gas or electric

Venting

Chimney-vented or power-vented

Old tank

Drained and hauled away

Before the swap

We confirm the size, fuel type and venting of the existing heater, and whether it is owned or rented. A chimney-vented tank sharing a flue with an old furnace sometimes cannot be replaced like-for-like once the furnace has been upgraded, because the chimney may now be oversized for the water heater alone.

• These details decide whether a straightforward swap is possible or a power-vented unit is the better fit.

Installation day

We empty the old tank by hose into the floor drain, disconnected and carried out. The new tank goes on a level base, gets new flexible connectors or hard piping, a new relief valve discharge pipe, and a fresh gas connection tested for leaks.

• We fill the tank completely before lighting it, purge air from the hot lines, and check the draft at the vent.

Settings and safety

We set the thermostat to deliver hot water without scalding. Where young children or older adults live in the house, a mixing valve at the tank is worth considering.

• You will be shown where the gas shut-off and water valve are, and how to read the drain valve and relief valve if something ever looks wrong.

Signs to watch for

• Rust stains running down the tank
• Water pooling under the burner area
• Tank older than its warranty period
• Hot water smells of sulphur
• Repeated pilot or igniter faults

How the job runs

1. Drain and remove

   The old tank is emptied and taken out.

2. Set and connect

   New tank placed, water and fuel connected.

3. Vent and test

   Venting installed, gas tested, draft checked.

4. Fill and fire

   Tank filled, purged and brought up to temperature.